Alan, Thanks for the tip. There are lots of mechanics notations and methods, but I'm not sure I'd use many of them for teaching mechanics because the more advanced math principles often hide the forest for the trees for engineering students. These newer methods based on Geometric and Clifford algebra are good for computational efficiency and succinctness of notation but that's more useful for people that already understand the principles of mechanics.
Jason moorepants.info +01 530-601-9791 On Mon, Feb 14, 2022 at 7:26 PM Alan Bromborsky <abrombo...@gmail.com> wrote: > For the people developing and maintaining the mechanics modules, you may > want to look at the following book which treats mechanics problems with > some new methods. Describing rotations is greatly simplified - > > https://link.springer.com/book/10.1007/0-306-47122-1 > On 2/14/22 12:40 PM, Peter Stahlecker wrote: > > Dear Jason, > > As to the speed of the new terms, I simply tried it, using the equations > of motion of a one body pendulum. > There is no difference to the older terms: > > with the *body* version the the rhs has 863, 824 operations. > with the axis version, 2 intermediate frames, the rhs has 43,722 > operations. > > The operations count was *exactly* the same with older and newer terms. > > Take care, Peter > > On Mon 14. Feb 2022 at 18:04 Peter Stahlecker <peter.stahlec...@gmail.com> > wrote: > >> Dear Jason, >> >> Just read you latest addition about vectors and reference frames. >> Small question: >> In order to rotate a frame relative to another one, you use these terms >> *A.orient_axis(N, ..)* >> *A.orient_body_fixed(N, …)* >> >> I assume, these are the new versions for >> A.orientnew(N, ‚Axis‘, …) >> A.orientnew(N, ‚Body, …) >> >> You might recall, that I ‚empirically‘ found that the *Body* version >> created much larger equations of motion compared to using ‚intermediate ‚ >> *Axis*‘ versions. >> >> Is it better to use *orient_body_fixed,* to avoid this issue of larger >> equations of motion? >> >> Thanks & take care! >> Peter >> >> >> >> On Sun 6. Feb 2022 at 08:19 Peter Stahlecker <peter.stahlec...@gmail.com> >> wrote: >> >>> Dear Jason, >>> >>> Thanks a lot for your explanation! Clear! >>> I checked on metaclasses, but I must admit I mostly understood, that a >>> simple user like me should not mess with them! :-)) >>> >>> Peter >>> >>> On Sun 6. Feb 2022 at 07:49 Jason Moore <moorepa...@gmail.com> wrote: >>> >>>> Peter, >>>> >>>> All `dynamicsymbols` is, is: >>>> >>>> f = Function('f') >>>> t = symbols('t') >>>> f_of_t = f(t) >>>> >>>> The last line `f(t)` is generating a new class of type f, instead of >>>> using a predefined class (look up metaclasses). So the user, typically not >>>> aware of this element in Python, is confused about what they are working >>>> with in the last line. It is just the way SymPy Function works. There are >>>> open issues about trying to change it to something more sensible for the >>>> user to understand. >>>> >>>> Jason >>>> moorepants.info >>>> +01 530-601-9791 >>>> >>>> >>>> On Sun, Feb 6, 2022 at 7:39 AM Peter Stahlecker < >>>> peter.stahlec...@gmail.com> wrote: >>>> >>>>> My question is more for my ‚general education‘ in sympy. >>>>> >>>>> I write this little program >>>>> >>>>> *from sympy.physics.mechanics import ** >>>>> *import sympy as sm* >>>>> *a = dynamicsymbols(‚a‘)* >>>>> *b = sm.symbols(‚b‘)* >>>>> >>>>> *print(‚type of a:‘, type(a))* >>>>> *print(‚type of b:‘, type(b))* >>>>> >>>>> I get this result: >>>>> >>>>> *type of a: a* >>>>> *type of b: class sympy.core.symbols.Symbols* >>>>> >>>>> Is seems that *a* does not have a type. How can that be? I thought in >>>>> python ‚everything‘ has a type. >>>>> >>>>> Thanks! >>>>> Any explanation is highly appreciated! >>>>> >>>>> >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "sympy" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to sympy+unsubscr...@googlegroups.com. >>>>> To view this discussion on the web visit >>>>> https://groups.google.com/d/msgid/sympy/5db2836e-44a8-428f-8b82-c56b2b2b5b20n%40googlegroups.com >>>>> <https://groups.google.com/d/msgid/sympy/5db2836e-44a8-428f-8b82-c56b2b2b5b20n%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>> . >>>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "sympy" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to sympy+unsubscr...@googlegroups.com. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/sympy/CAP7f1Ajkjs%3DNhJOhrFXmEpLJ6nv0TM9FgHXg%3DS1kSCF-6Cw5zw%40mail.gmail.com >>>> <https://groups.google.com/d/msgid/sympy/CAP7f1Ajkjs%3DNhJOhrFXmEpLJ6nv0TM9FgHXg%3DS1kSCF-6Cw5zw%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>> -- >>> Best regards, >>> >>> Peter Stahlecker >>> >> -- >> Best regards, >> >> Peter Stahlecker >> > -- > Best regards, > > Peter Stahlecker > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sympy+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/CABKqA0YLxUq3drDz4Zz5rM_bsE9nhLtf8onVhG_86eXxrAhL0w%40mail.gmail.com > <https://groups.google.com/d/msgid/sympy/CABKqA0YLxUq3drDz4Zz5rM_bsE9nhLtf8onVhG_86eXxrAhL0w%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sympy+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/e3b6256c-5013-de21-8b44-9d9ddd8b027f%40gmail.com > <https://groups.google.com/d/msgid/sympy/e3b6256c-5013-de21-8b44-9d9ddd8b027f%40gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "sympy" group. 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